picture of the day

http://bit.ly/2R9tFdG http://bit.ly/2Vx0oI9 Paraboloide circular 02.jpg January 5, 2019 Circular paraboloid generated by z = − a ( x 2 + y 2 ) , a > 0 {\displaystyle z=-a(x^{2}+y^{2}),a>0} .